Despite strict Covid-19 restrictions, NSW’s deadly Delta outbreak could reach thousands of cases per day later this month new modelling suggests.
Researchers with the Burnet Institute published their study on Insight Plus on Monday as the state announced 207 new local coronavirus cases. It is the third day in a row that cases have surpassed 200.
The group took NSW cases reported last month and applied them to a model based on an analysis of what did and didn't work in containing Melbourne's major outbreak last year.
The study focused on case trends in individual NSW Local Health Authorities to create a model showing what Sydney could face in the coming weeks.
Applying the restrictions in force as of July 29 using data up until that date the study predicted Sydney will record about 570 cases per day by Friday.
“This is the result of stable or falling daily cases in south west Sydney Local Health District (LHD) being exceeded by rising cases elsewhere,” researchers said.
Cases have momentarily plateaued since then, remaining above 200, but not rising beyond the 239 recorded on both Thursday and Sunday.
Unless further restrictions are imposed, the modelling at the time predicted 7700 new daily Covid cases by August 25.
The NSW lockdown is expected to end on August 28, a goal premier Gladys Berejiklian says she still believes the state will reach.
Covid cases double every nine days
Over the past six weeks up until July 29, cases doubled every nine days on average, experts with the Burnet Institute said.
“Although the number of cases is still lower outside south west Sydney, daily cases in the rest of Sydney are now increasing at about the same rate as happened initially in Fairfield – doubling every 4–5 days,” they wrote.
While it is unclear why the cases are increasing, it is “statistically significant,” researchers said on completion of the study, adding that NSW Government has recognised the issue by imposing more stringent rules in the areas of Georges River, Campbelltown and Parramatta.
However, the Burnet Institute said the LGAs of Burwood and Strathfield, in Sydney’s west, had “higher incidences per capita” from July 19 to July 26 compared to either Parramatta and Campbelltown.
Despite this, stricter restrictions in those areas have not been imposed.
Sydney Covid outbreak is game of 'whack a mole'
Burnet researchers compared the community outbreaks to the children’s game “whack a mole”.
“The reality is that no one is safe until everyone is safe. Every positive case, no matter in which LGA, takes testing and contact tracing resources and has the potential to trigger new outbreaks,” they said.
To avoid thousands of new cases later this month, experts said more stringent restrictions should be introduced across Sydney, not just the eight LGAs already outlined.
Even with these measures, Sydney should brace itself in the coming months as modelling shows numbers would not reduce to a five-per-day average until late September.
“We sincerely hope we are wrong, and the daily case load drops much faster,” researchers said, adding that the only things that will drop cases are people abiding by the lockdown and an increase in vaccines.
Modelling also shows that if lockdown had not been introduced on June 26, Sydney would have seen 1000 new cases a day by the end of July.
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